The present invention relates to a technology effective when applied to the device structure and manufacturing process of a power semiconductor device (or semiconductor integrated circuit device).
There is disclosed in Japanese Patent Laid-Open No. 2008-124346 (Patent Document 1) or U.S. Pat. No. 7,642,597 (Patent Document 2) an example of a power MOSFET (metal oxide semiconductor field effect transistors) having a so-called semi-super junction structure, that is, a structure manufactured using a multi-epitaxy system or an epitaxy trench filling system and having a super junction structure introduced halfway through a drift region. According to the description on this example, by creating an impurity profile in which an impurity concentration gradually reduces downward in a P-column region constituting a semi-super junction structure, electric field concentration can be relaxed at the lower end portion of a trench field plate and thereby high breakdown voltage and low ON resistance can be achieved.
There is disclosed in Japanese Patent Laid-Open No. 2004-119611 (Patent Document 3) an example of a power MOSFET having a semi-super junction structure manufactured using mainly a multi-epitaxy system. According to the description on this example, by creating an impurity profile in which an impurity concentration increases gradually downward in an N-column region constituting a semi-super junction structure, a decline in breakdown voltage due to a charge imbalance between the N-column region and P-column region can be reduced.
There is disclosed in Japanese Patent Laid-Open No. 2008-258442 (Patent Document 4) or U.S. Patent Publication No. 2008-246079 (Patent Document 5) an example of a power MOSFET having a semi-super junction structure manufactured using mainly a multi-epitaxy system. According to the description on the example, by creating an impurity profile having a peak at the center portion thereof in an N-column region and a P-column region constituting a semi-super junction structure, depletion at the upper and lower ends is facilitated and thereby electric field concentration is relaxed.
There is disclosed in Japanese Patent Laid-Open No. 2008-91450 (Patent Document 6) or U.S. Patent Publication No. 2008-237774 (Patent Document 7) an example of a power MOSFET having a semi-super junction structure manufactured using mainly a multi-epitaxy system. According to the description on this example, by creating an impurity profile in which an impurity concentration shows a stepwise decrease downward in an N-column region and a P-column region constituting a semi-super junction structure, high breakdown voltage and low ON resistance can be achieved.
There is disclosed in Japanese Patent Laid-Open No. 2007-300034 (Patent Document 8) or U.S. Patent Publication No. 2008-17897 (Patent Document 9) an example of a power MOSFET having a semi-super junction structure manufactured using mainly an epitaxy trench filling system. According to the description on this example, by differentiating the upper width and the lower width between an N-column region and a P-column region constituting a semi-super junction structure (more specifically, by thinning the lower width of the P-column region), diffusion of boron at the lower portion of the column is suppressed and an increase in the ON resistance can be prevented.
There is disclosed in Japanese Patent Laid-Open No. 2006-66421 (Patent Document 10) or U.S. Pat. No. 7,420,245 (Patent Document 11) an example of a power MOSFET manufactured using a multi-epitaxy system and having a so-called full-super junction structure (which may also be called “super junction structure” simply), that is, having a super junction structure introduced therein in such a manner that it penetrates through a drift region. According to the description on this example, each of an N-column region and a P-column region constituting the super junction structure has upper and bottom sections and by increasing the concentration of the upper section, a decrease in breakdown voltage due to a charge imbalance between the N-column region and the P-column region can be reduced.    [Patent Document 1] Japanese Patent Laid-Open No. 2008-124346    [Patent Document 2] U.S. Pat. No. 7,642,597    [Patent Document 3] Japanese Patent Laid-Open No. 2004-119611    [Patent Document 4] Japanese Patent Laid-Open No. 2008-258442    [Patent Document 5] U.S. Patent Publication No. 2008-246079    [Patent Document 6] Japanese Patent Laid-Open No. 2008-91450    [Patent Document 7] U.S. Patent Publication No. 2008-237774    [Patent Document 8] Japanese Patent Laid-Open No. 2007-300034    [Patent Document 9] U.S. Patent Publication No. 2008-17897    [Patent Document 10] Japanese Patent Laid-Open No. 2006-66421    [Patent Document 11] U.S. Pat. No. 7,420,245